FIG. 1 is a partial sectional view of a conventional transmission device of a fan. The fan comprises a fan main body 1. The fan main body 1 is provided with a geared motor 2 therein. The fan main body 1 is pivotally connected to one end of a main rod 4 through at least one pivot member 3 so that the fan main body 1 is rotatable relative the main rod 4 and formed with a swing direction. The geared motor 2 is connected with a spindle 6 through at least one gear 5 and is fixed to the central axis of a transmission member 7 through the spindle 6. An eccentric position of the transmission member 7 is connected with a connecting rod 8. The transmission member 7 is connected with the main rod 4 through the connecting rod 8 and the pivot member 3. When the fan is assembled, the other end of the main rod 4 is fixed to a wall or a ceiling. When the fan is activated, the fan main body 1 can be swung back and forth in the swing direction by the driving of the geared motor 2.
The conventional fan can be swung back and forth through the transmission member 7. When the user wants to change the angle of the fan main body 1, the fan main body 1 is usually pulled by hand to forcibly turn the fan body 1. However, the fan main body 1 is connected to the transmission member 7 through the geared motor 2, the gear 5, and the spindle 6. When the user applies a force to pull the fan main body 1 for changing the angle of the fan main body 1 in the swing direction, the applied force exerted by the user indirectly affects the geared motor 2, the gear 5, and the spindle 6. The geared motor 2, the gear 5 and the spindle 6 may have gear slipping or gear jumping easily. After a long time, the clearance between the geared motor 2, the gear 5 and the spindle 6 may increase. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.